Oligomerization catalyst systems, methods for preparing such catalysts and methods for using such catalyst systems for preparing oligomerization products are known in the art, including processes and products for the catalytic oligomerization of ethylene and propylene. Such oligomerization catalyst systems, methods for preparing such catalysts and methods for using such catalyst systems for preparing oligomerization products have included complex, sensitive organometallic metal/ligand homogenous catalysts.
For example, conversion of olefins to gasoline and/or distillate products is disclosed in U.S. Pat. Nos. 3,960,978 and 4,021,502 wherein gaseous olefins in the range of ethylene to pentene, either alone or in admixture with paraffins, are converted into an olefinic gasoline blending stock by contacting the olefins with a catalyst bed made up of a ZSM-5 type zeolite.
U.S. Pat. No. 4,504,693 describes a process for converting feedstock comprising lower olefins to form higher hydrocarbons comprising a major amount of distillate product, wherein the olefinic feedstock is combined with a pressurized stream comprising olefins in the presence of a zeolite oligomerization catalyst under elevated temperature in a pressurized reactor zone. U.S. Pat. No. 4,504,693 describes a crystalline zeolite of the ZSM-5 type oligomerization catalyst for converting olefinic feedstocks containing C2-C6 alkenes at elevated temperature and pressure.
U.S. Pat. No. 4,511,750 describes a process for oligomerizing propylene and butenes, which includes use of a catalyst having nickel sulfate associated with a porous, refractory, inorganic oxide. In this process, the catalyst is contacted with a gas comprising oxygen at a temperature in the range from about 750 F to about 1150 F for at least 2 hours and contacting the resulting catalyst with an inert gas at a temperature of about 350 F to about 750 F for at least 1 hour.
U.S. Pat. No. 8,471,085 describes an olefin oligomerization system and process, including a catalyst having a transition metal compound and a pyrrole compound, wherein the pyrrole compound has a hydrogen atom at the 5-position or at the 2- and 5-position and a bulky substituent located on each carbon atom adjacent to the carbon atom bearing a hydrogen atom at the 5-position or the 2- and 5-positions, and a metal alkyl. According to U.S. Pat. No. 8,471,085, the productivity of certain oligomerization system and processes is acutely affected by variations in temperature.
Use of a catalyst in contact with ethylene in a dilute ethylene stream to produce heavier hydrocarbons has been described. For example, U.S. Pat. No. 8,021,620 describes a catalyst comprising an amorphous silica-alumina base, with a Group VIII and/or VIB metal, which catalyst is described as being resistant to hydrogen sulfide, carbon oxides, hydrogen and ammonia. As described in U.S. Pat. No. 8,021,620, a dilute ethylene feed is contacted with the oligomerization catalyst at a temperature between about 200° C. and about 400° C.
Thus, improved materials and methods for the oligomerization of ethylene and propylene in refinery streams are of interest.